On Thu, May 31, 2018 at 8:07 AM, Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> wrote: > On Thu, May 31, 2018 at 11:27:33AM +0900, Yasunori Goto wrote: >> Hello, >> >> >> I would like to know about the Experimental message of Filesystem DAX. >> -------------------------------------------------------- >> DAX enabled. Warning: EXPERIMENTAL, use at your own risk >> -------------------------------------------------------- >> >> AFAIK, the final issue of Filesystem DAX is metadata update problem, >> and it is(will be?) solved by great effort of MAP_SYNC and >> "fix dma vs truncate/hole-punch" patch set. >> So, I suppose that the Experimental message can be removed, >> but I'm not sure. >> >> Is it possible? >> Otherwise, are there any other issues in Filesystem DAX yet? >> >> If this is silly question, sorry for noise.... >> >> Thanks, >> --- >> Yasunori Goto > > Adding in the XFS and ext4 developers, as it's really their call when to > remove this notice. > > We've talked about this off and on for a long while, but IMHO we should remove > the EXPERIMENTAL warning. The last few things that we had on our TODO list > before this was removed were: > > 1) Get consistent handling of the DAX mount option. We currently have this, > as both filesystems will behave the same and fall back and remove the DAX > mount option if it is unsupported by the block device, etc. > > 2) Get consistent handling of the DAX inode option. We currently have this, > as all DAX behavior now happens through the mount option. If/when we > re-enable the per-inode DAX flag we should do it consistently for all DAX > enabled filesystems. > > 3) Make DAX work with other XFS features like reflink, etc. This one isn't > done, but we at least disallow DAX with XFS features like reflink where it > could be an issue. Darrick, do you still feel like we need to get these > working together to remove EXPERIMENTAL, or are you happy enough that we're > keeping them separated and that we're keeping user data safe? > > Jan and the other ext4 guys, do you have any additional things you need done > before removing the EXPERIMENTAL warning from ext4 + DAX? The one's on my list are: 1/ Get proper support for recovering userspace consumed poison in DAX mappings (may not make 4.18) 2/ The DAX-DMA vs Truncate fix (queued for 4.18).
